FIG. 4 is a longitudinal cross sectional view showing a conventional fuel supply apparatus disclosed, for example, in the Japanese Patent Publication (unexamined) No. 294282/1999. FIG. 5 is a cross sectional view taken along the line V—V of FIG. 4.
Generally a vehicle such as automobile is mounted with a fuel tank 1 for supplying fuel to an internal combustion engine such as engines. A fuel supply apparatus 3 is mounted at an opening 2 of the fuel tank 1.
A filter-equipped pump 4 includes a fuel pump part 5 that pumps fuel and feeds the fuel to the internal combustion engine such as engine and a fuel filter part 6 that removes foreign substances mixed into the fuel, and the fuel pump part and the fuel filter part are integrally formed into a cylindrical shaped filter-equipped pump 4. This cylindrical filter-equipped pump 4 possesses an integral construction in which a tubular fuel filter part 6 is fitted concentrically around an outer circumference of the cylindrical fuel pump part 5, and is formed into an integral structure.
A disk-shaped intake filter 7, which communicates with an intake port of the fuel pump part 5, is mounted on a bottom of the filter-equipped pump 4. A discharge port of the fuel pump part 5 and an inlet of the fuel filter part 6 are connected together with the use of a flexible tube 8. Further, another flexible tube 10, which is provided with a joint 9 at a tip portion, is connected to an outlet of the fuel filter part 6.
In the fuel tank 1, there is provided a bottomed reservoir 12 having a cylindrical shape that is in contact with a bottom 11 of the fuel tank 1 and houses the filter-equipped pump 4. This reservoir 12 is arranged so as to cause a predetermined volume of fuel to be retained at all times so that the fuel pump part 5 may pump the fuel without fail, even in the case where the fuel tank 1 becomes inclined and the fuel in the fuel tank 1 is retained at one side. There is provided a fuel inlet 13, which communicates with an internal part of the fuel tank 1, at the bottom portion of the reservoir 12.
Meanwhile, the fuel tank 1 is provided with a lid 14 to be mounted in an opening 2, which is formed at a top surface thereof. Through this lid 14, there is provided a fuel discharge passage part 15 to which the joint 9 at the tip portion of the flexible tube 10 connected to the outlet of the fuel filter part 6. A reservoir mounting wall 16 of a cylindrical shape or a partially cylindrical shape is molded on a back side (inside part of the fuel tank 1) of the lid 14, extending toward an axial direction 17 of the above-mentioned reservoir 12 so as to surround the fuel discharge passage part 15.
Furthermore, the reservoir-mounting wall 16 is formed so that inner diameter thereof may be substantially the same as or slightly larger than outer diameter of the filter-equipped pump 4, as well as outer diameter thereof may be substantially the same as or slightly smaller than inner diameter of the above-mentioned reservoir 12, thus capable of being inserted between the filter-equipped pump 4 and the reservoir 12.
A guide void 18, which extends in the axial direction 17, is formed at plural positions of a circumferential direction in an internal part of the reservoir 12; as well as a guide rod 19 (also refer to FIG. 5) is formed, which is fitted in a slidable manner into the guide void 18 in plural positions of the reservoir-mounting wall 16 corresponding to the guide voids 18. An elastic member 20 such as coil spring is interposed between the guide void 18 and the guide rod 19 to constitute a return mechanism 21. The reservoir 12 can move resiliently with respect to the lid 14 due to an elastic force provided by the elastic member 20 such as coil spring.
An engaging detent 22 is formed in plural positions of a circumferential direction on the outside of the reservoir mounting wall 16; as well as a plurality of catching slots 23, which extend in the axial direction 17, and in which the engaging detents 22 are caught and held movably, are formed at the reservoir 12 in the positions corresponding to the engaging detents 22. In addition, numeral 24 designates a liquid measure, and numeral 25 designates a flexible tube of a fuel return passage part.
In the fuel supply apparatus 3 constructed as described above, at the time of inserting the reservoir 12 into the opening 2 of the fuel tank 1 and thereafter mounting the lid 14 in the opening 2, an entire length of the fuel supply apparatus 3 is adjusted in the following manner. That is, since the reservoir 12 and the lid 14 are fitted in a telescopic manner due to an impetus provided by the elastic member 20 such as coil spring, the bottom of the reservoir 12 comes in contact with a bottom surface 11 of the fuel tank 1 whereby the reservoir 12 travels with respect to the lid 14 telescopically, and an entire length of the fuel supply apparatus 3 is adjusted so as to match depth of the fuel tank 1.
Now, flow of the fuel in the fuel supply apparatus 3 is described. As shown in FIG. 4, when driving the fuel pump part 5 of the filter-equipped pump 4, the fuel in the reservoir 12 is pumped through the disk-shaped inlet filter 7, which is attached to the intake side of the fuel pump part 5, and relatively large foreign substances, which have been mixed into the fuel, are removed through the intake filter 7.
Then, the fuel having been discharged from the discharge port of the fuel pump part 5 is sent to the inlet of the fuel filter part 6 disposed around the outer circumference of the fuel pump part 5 through the flexible tube 8, gets in the fuel filter part 6 from the inlet thereof, and flows in the fuel filter part 6 so as to run around the outer circumference of the fuel pump part 5, whereby foreign substances having been contained in the fuel are filtered and removed. The fuel having got out of the outlet of the fuel filter part 6 flows in the fuel discharge passage part 15 provided through the lid 14, by way of the flexible tube 10. Subsequently, the fuel is fed to the internal combustion engine such as engine through a fuel hose, not shown, from the fuel discharge passage part 15.
In the conventional fuel supply apparatus 3, as described above, the guide void 18, which extends in an axial direction, is formed in plural positions of a circumferential direction in an internal part of the reservoir 12; and the rod-shaped guide rod 19, which fits in the guide void 18 in a slidable manner at the positions corresponding to the guide voids 18 on the reservoir mounting wall 16. Further, the elastic member 20 such as coil spring is interposed between the guide void 18 and the guide rod 19, resulting in constitution of the return mechanism. The reservoir 12 and the lid 14 are made telescopic due to an elastic force provided by the elastic member 20. Accordingly, the coil spring is located in a narrow space sandwiched between an inner wall of the reservoir 12 and an outer circumference of the filter-equipped pump 4 to constitute an elastic function, and therefore a large average diameter of the coil spring cannot be achieved. Further, since a load change per deflection length of the coil spring becomes large, adaptability for dimensional change of the fuel tank gets worse, and load applied to the tank becomes larger. Moreover, since a plurality of coil springs are disposed at a circumferential portion apart from a central portion of the reservoir 12, a problem exists in that unbalance occurs in pressure load, whereby the reservoir 12 is not pressed stably to the fuel tank 1.
Moreover, since the fuel filter part 6 is located in a position proximate to the bottom of an internal part of the reservoir 12, a retention volume of fuel comes to be smaller by the amount corresponding to the volume of the fuel filter part 6. Therefore, in the state in which a fuel liquid level is, low, inclination of the fuel tank makes it difficult to pump the fuel. As a measure of this trouble, another problem exists in that a reservoir grows in size.
The present invention was made to solve such problems as described above and has an object of providing a fuel supply apparatus capable of stably adapting to change in tank dimension without applying any excessively large load onto the fuel tank.
The present invention has another object of providing a more compact fuel supply apparatus.